Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$159.85	13.395%	$181.2619	$181.26	$181.25	$181.30
Purchase #2	$98.98	5.627%	$104.5496	$104.55	$104.55	$104.50
Purchase #3	$194.89	12.134%	$218.538	$218.54	$218.55	$218.50
Purchase #4	$194.44	13.617%	$220.9169	$220.92	$220.90	$220.90
Purchase #5	$96.93	7.356%	$104.0602	$104.06	$104.05	$104.10
Purchase #6	$180.61	11.162%	$200.7697	$200.77	$200.75	$200.80
Purchase #7	$153.60	8.123%	$166.0769	$166.08	$166.10	$166.10
7 purchase totals =	$1,079.30		$1,196.1732	$1,196.18	$1,196.15	$1,196.20